I'm gonna try to keep this short as I worked with autistic kids when I thought I wanted to be a psych major in college.
Some of those kids are very irrational and would say things that they didn't understand or necessarily mean. One day they would be like I hate you, then love you the next. Instructors don't believe in discipline, they don't teach them that the world doesn't care about them being autistic, they believe in enabling kids that don't have fully have a grasp on what they're saying, they just practice reinforcement because they literally told me on day one that you don't say "no" you are to provide support and redirect and if that doesn't work then embrace their desire. That shyt does not prepare kids for the future, it teaches kids that if they act out enough that they can get what they want. I knew then that that wasn't for me.
I remember there was a kid that would literally grab a teacher's titty because he liked them and the teacher wouldn't say no, she would be like if you want alone time in the bathroom then just say you want privacy. So eventually I found out that he went to a regular school and threw a fit and started breaking shyt in class because another girl wouldn't let him touch her. That's the type of shyt they encourage now, that's why I switched my major. They pacify kids and give them power that they aren't equipped to handle.
I say all this to say, this is probably what happened in this case. They empowered a kid that probably didn't even understand what he was saying. He probably felt that way one day, they encouraged it and now he's convinced because some autistic kids will literally just parrot things they hear whether they feel that way or not. I even remember another kid that said he hated his sister and come to find out he didn't even have one, he just heard another kid say it and saw they were getting attention and decided to say it too.